Relationship between childhood trauma and paranoia: a study of specificity and underlying theoretical mechanisms
Carmichael, David Andrew
Purpose: While biogenetic theories have traditionally dominated understandings of psychosis, there is now a large body of evidence suggesting a causal relationship between childhood trauma and psychosis. We sought to further study this relationship by adopting a psychotic experience specific approach and applying two of Bradford Hill’s causality criteria, namely specificity and underlying theoretical mechanisms, to the relationship between childhood trauma and paranoia. Method: Chapter 1 was a systematic review and meta-analysis that sought to examine the magnitude of the association between childhood sexual (CSA), physical (CPA) and emotional abuse (CEA) and physical (CPN) or emotional neglect (CEN) and paranoia across community and clinical samples. Chapter 2 is an empirical research study that sought to test whether negative core schema mediated the relationship between childhood trauma and paranoia. Study 1 sought to these relationships within the general population, whereas Study 2 aimed to test these in a clinical sample of people with persecutory delusions. We also sought to pilot a new measure of negative core schema, The Schema Rating Scale (SCIRATS). Correlation and mediation analysis were utilised to test our empirical study hypothesis. Results: Our meta-analysis found small associations between all forms of childhood trauma and paranoia examined, however the magnitude of the association may be somewhat greater for CEA and CPA than for the other forms of childhood we examined and paranoia . In Study 1, we found that negative-self, negative-other and both negative-self and negative-other core schema mediated the relationship between childhood trauma and paranoia. We found similar results when repeating these analyses with the SCIRATS. In Study 2, we found significant associations between childhood trauma and negative-self core schema that remained significant on the SCIRATS. Negative-self and negative-other core schema were also significantly associated with paranoia however, when we repeated this analysis with the SCIRATS, only negative-self core schema remained significant. We found no significant association between childhood trauma and paranoia. Positive initial feedback on the SCIRATS would suggest participants view this as an acceptable measure. Conclusions: Whilst acknowledging the limitations associated with our studies, our findings suggest that while there appears to be a general association between the forms of childhood trauma we examined and paranoia, this relationship may be somewhat greater for CEA and CPA and paranoia. They are consistent with cognitive models of psychosis and suggest that negative core schema may be important underlying mechanisms in the relationship between childhood trauma and paranoia. We make recommendations for future research to further examine the evidence for specificity and recommend that individuals with psychosis should be asked about childhood trauma and that future research should further examine the potential benefits of trauma-informed formulation and psychological therapies targeting negative core schema in reducing paranoia.